This invention relates to sewing devices and more particularly to a method and an apparatus for button sewing.
Japanese utility model No. 45-13643 describes the background of the present invention. According to this publication, after sewing the button on to the horizontal workpiece, the button is turned vertically and the workpiece is moved horizontally per each needle's one up-down motion such that the thread wraps around the button neck portion to perform "button-neck-wrapping".
The present invention addresses a problem which arises when a stay button and a surface button are sewed to a thick workpiece like a coat material or a knitted material. It is impossible to simultaneously sew both a stay button and a surface button by placing the surface button at upper side of the material and the stay button at lower the side of the material, and then conduct button-neck-wrapping after finishing button sewing. According to the conventional way of button-neck-wrapping, after the button is sewn, the button is turned vertically and the button is moved horizontally when the needle performs one reciprocal motion such that the needle drops both sides of sewn thread. The manual way of button-neck-wrapping, compares favorably with the conventional apparatus because, manual results in a more uniform and of a higher sewing quality end produce.
The present invention provides a solution comprising an upper-needle-bar and a lower-needle-bar which are aligned vertically and conduct up-down motion in association with the drive motor, the driving device which drives the workpiece and the button in the X-Y direction. The needle with the eyed thread having definite length for sewing is arranged to travel between the upper-needle-bar-spindle and the lower-needle-bar-spindle and is received alternately per each needle stroke such that buttons are sewn in a manner closely simulating "hand" sewing. After sewing the button, the button is upturned from the needle's vertical pass-way, and received in the lower-needle-bar-spindle so that it penetrates upward into the workpiece. After the needle is received in the upper-needle-bar-spindle, the button is turned down to resume the original position. The thread is then pulled and guided into a position just under the needle point. The surface button is then released from the clamping jaw but its bottom portion is supported by the bifurcated holder, and then the driving device performs "button-neck-wrapping" by driving the workpiece in a circular and horizontal motion around the thread guide positioned just under the needle point.